diff --git a/src/M5UnitUnifiedMETER.h b/src/M5UnitUnifiedMETER.h
index 9b2eedf..e51bbf8 100644
--- a/src/M5UnitUnifiedMETER.h
+++ b/src/M5UnitUnifiedMETER.h
@@ -5,6 +5,7 @@
  */
 /*!
   @file M5UnitUnifiedMETER.h
+  @brief Header for M5UnitUnifiedMETER (C compatible include)
  */
 #ifndef M5_UNIT_UNIFIED_METER_H
 #define M5_UNIT_UNIFIED_METER_H
diff --git a/src/unit/unit_ADS111x.cpp b/src/unit/unit_ADS111x.cpp
index 13444a4..6903d35 100644
--- a/src/unit/unit_ADS111x.cpp
+++ b/src/unit/unit_ADS111x.cpp
@@ -27,7 +27,7 @@ constexpr float coefficient_table[] = {
     1024.f / 32767,
     512.f / 32767,
     256.f / 32767,
-    // dupicated[6,7]
+    // duplicated[6,7]
     256.f / 32767,
     256.f / 32767,
 };
@@ -241,7 +241,8 @@ bool UnitADS111x::writeThreshold(const int16_t high, const int16_t low)
         M5_LIB_LOGW("high must be greater than low");
         return false;
     }
-    return writeRegister16BE(HIGH_THRESHOLD_REG, (uint16_t)high) && writeRegister16BE(LOW_THRESHOLD_REG, (uint16_t)low);
+    return writeRegister16BE(HIGH_THRESHOLD_REG, static_cast<uint16_t>(high)) &&
+           writeRegister16BE(LOW_THRESHOLD_REG, static_cast<uint16_t>(low));
 }
 
 //
diff --git a/src/unit/unit_ADS111x.hpp b/src/unit/unit_ADS111x.hpp
index b8596fa..15cab9c 100644
--- a/src/unit/unit_ADS111x.hpp
+++ b/src/unit/unit_ADS111x.hpp
@@ -286,14 +286,17 @@ public:
     ///@warning ADS1113, ADS1114 and ADS1115 differ in the items that can be set
     ///@name Configuration
     ///@{
-    /*! @brief Gets the input multiplexer */
+    //! @brief Gets the input multiplexer
+    //! @return Current multiplexer setting
     inline ads111x::Mux multiplexer() const
     {
         return _ads_cfg.mux();
     }
     //! @brief Gets the programmable gain amplifier
+    //! @return Current gain setting
     ads111x::Gain gain() const;
     //! @brief Gets the sampling rate
+    //! @return Current sampling rate
     inline ads111x::Sampling samplingRate() const
     {
         return _ads_cfg.dr();
@@ -326,28 +329,43 @@ public:
         return _ads_cfg.comp_lat();
     }
     //! @brief Gets the comparator queue
+    //! @return Current comparator queue setting
     inline ads111x::ComparatorQueue comparatorQueue() const
     {
         return _ads_cfg.comp_que();
     }
 
     //! @brief Write the input multiplexer
+    //! @param mux Multiplexer setting
+    //! @return True if successful
     virtual bool writeMultiplexer(const ads111x::Mux mux) = 0;
     /*!
       @brief Write the programmable gain amplifier
+      @param gain Gain setting
+      @return True if successful
       @warning the threshold values must be updated whenever the PGA settings are changed
       @sa writeThreshold
      */
     virtual bool writeGain(const ads111x::Gain gain) = 0;
-    /*! @brief Write the data rate  */
+    //! @brief Write the data rate
+    //! @param rate Sampling rate
+    //! @return True if successful
     bool writeSamplingRate(const ads111x::Sampling rate);
     //! @brief Write the comparator mode
+    //! @param b true: Window comparator, false: Traditional comparator
+    //! @return True if successful
     virtual bool writeComparatorMode(const bool b) = 0;
     //! @brief Write the comparator polarity
+    //! @param b true: Active high, false: Active low
+    //! @return True if successful
     virtual bool writeComparatorPolarity(const bool b) = 0;
     //! @brief Write the latching comparator
+    //! @param b true: Latching, false: Nonlatching
+    //! @return True if successful
     virtual bool writeLatchingComparator(const bool b) = 0;
     //! @brief Write the comparator queue
+    //! @param c Comparator queue setting
+    //! @return True if successful
     virtual bool writeComparatorQueue(const ads111x::ComparatorQueue c) = 0;
     ///@}
 
@@ -363,7 +381,7 @@ public:
       @warning Until it can be measured, it will be blocked until the timeout
       time
     */
-    bool measureSingleshot(ads111x::Data& d, const uint32_t timeoutMillis = 1000U);
+    bool measureSingleshot(ads111x::Data& data, const uint32_t timeoutMillis = 1000U);
     ///@}
 
     ///@name Threshold
diff --git a/src/unit/unit_DualKmeter.hpp b/src/unit/unit_DualKmeter.hpp
index 3f01359..ccefeac 100644
--- a/src/unit/unit_DualKmeter.hpp
+++ b/src/unit/unit_DualKmeter.hpp
@@ -50,11 +50,11 @@ struct Data {
     std::array<uint8_t, 4> raw{};  //!< Raw data
     Channel channel{};             //!< Which channel?
 
-    //@note Unit depends on setting
+    //! @note Unit depends on setting
     inline float temperature() const
     {
-        return static_cast<int32_t>(((uint32_t)raw[3] << 24) | ((uint32_t)raw[2] << 16) | ((uint32_t)raw[1] << 8) |
-                                    ((uint32_t)raw[0] << 0)) *
+        return static_cast<int32_t>((static_cast<uint32_t>(raw[3]) << 24) | (static_cast<uint32_t>(raw[2]) << 16) |
+                                    (static_cast<uint32_t>(raw[1]) << 8) | static_cast<uint32_t>(raw[0])) *
                0.01f;
     }
 };
@@ -99,9 +99,9 @@ public:
         bool start_periodic{true};
         //! periodic interval(ms) if start on begin
         uint32_t interval{100};
-        //! //!< measurement channel if start on begin
+        //!< measurement channel if start on begin
         dual_kmeter::Channel measurement_channel{dual_kmeter::Channel::One};
-        //! //!< measurement unit if start on begin
+        //!< measurement unit if start on begin
         dual_kmeter::MeasurementUnit measurement_unit{dual_kmeter::MeasurementUnit::Celsius};
     };
 
@@ -135,17 +135,20 @@ public:
 
     ///@name Properties
     ///@{
-    /*! Gets the measurement unit on periodic measurement */
+    //! @brief Gets the measurement unit on periodic measurement
+    //! @return Current measurement unit
     dual_kmeter::MeasurementUnit measurementUnit() const
     {
         return _munit;
     }
-    /*! Gets the measurement channel on periodic measurement */
+    //! @brief Gets the measurement channel on periodic measurement
+    //! @return Current measurement channel
     dual_kmeter::Channel measurementChannel() const
     {
         return _channel;
     }
-    /*! Set the measurement unit on periodic measurement */
+    //! @brief Set the measurement unit on periodic measurement
+    //! @param munit Measurement unit to set
     void setMeasurementUnit(const dual_kmeter::MeasurementUnit munit)
     {
         _munit = munit;
@@ -220,18 +223,19 @@ public:
       @return True if successful
       @warning During periodic detection runs, an error is returned
     */
-    bool measureSingleshot(dual_kmeter::Data& d, const dual_kmeter::Channel channel,
+    bool measureSingleshot(dual_kmeter::Data& data, const dual_kmeter::Channel channel,
                            dual_kmeter::MeasurementUnit munit = dual_kmeter::MeasurementUnit::Celsius,
                            const uint32_t timeoutMs           = 100);
     /*!
       @brief Measure internal temperature single shot
       @param[out] data Measured data
+      @param channel Channel to be measured
       @param munit  measurement unit
       @param timeoutMs Measurement timeout time(ms)
       @return True if successful
       @warning During periodic detection runs, an error is returned
      */
-    bool measureInternalSingleshot(dual_kmeter::Data& d, const dual_kmeter::Channel channel,
+    bool measureInternalSingleshot(dual_kmeter::Data& data, const dual_kmeter::Channel channel,
                                    const dual_kmeter::MeasurementUnit munit = dual_kmeter::MeasurementUnit::Celsius,
                                    const uint32_t timeoutMs                 = 100);
     ///@}
diff --git a/src/unit/unit_EEPROM.hpp b/src/unit/unit_EEPROM.hpp
index eb94624..24cd678 100644
--- a/src/unit/unit_EEPROM.hpp
+++ b/src/unit/unit_EEPROM.hpp
@@ -39,19 +39,30 @@ public:
     {
     }
 
+    //! @brief Gets the expected (hope) ADC value for the given gain
+    //! @param gain Gain setting
+    //! @return Expected ADC value
     inline int16_t hope(m5::unit::ads111x::Gain gain) const
     {
         return _calibration[m5::stl::to_underlying(gain)].hope;
     }
+    //! @brief Gets the actual ADC value for the given gain
+    //! @param gain Gain setting
+    //! @return Actual ADC value
     inline int16_t actual(m5::unit::ads111x::Gain gain) const
     {
         return _calibration[m5::stl::to_underlying(gain)].actual;
     }
+    //! @brief Gets the calibration factor for the given gain
+    //! @param gain Gain setting
+    //! @return Calibration factor (hope / actual)
     inline float calibrationFactor(m5::unit::ads111x::Gain gain) const
     {
         return actual(gain) ? (float)hope(gain) / actual(gain) : 1.0f;
     }
 
+    //! @brief Read calibration data from EEPROM
+    //! @return True if successful
     bool readCalibration();
 
 protected:
diff --git a/src/unit/unit_INA226.cpp b/src/unit/unit_INA226.cpp
index 3034008..920479f 100644
--- a/src/unit/unit_INA226.cpp
+++ b/src/unit/unit_INA226.cpp
@@ -221,12 +221,12 @@ struct Mask {
     uint16_t v{};
 };
 
-float caluculate_currentLSB(const float maxCur)
+float calculate_currentLSB(const float maxCur)
 {
     return maxCur / 32767.f;
 }
 
-uint16_t caluculate_calibration(const float shuntRes, const float maxCur, const float curLSB)
+uint16_t calculate_calibration(const float shuntRes, const float maxCur, const float curLSB)
 {
     return (0.00512f / (curLSB * shuntRes));
 }
@@ -284,7 +284,7 @@ UnitINA226::UnitINA226(const float shuntRes, const float maxCurA, const float cu
     ccfg.clock = 400 * 1000U;
     component_config(ccfg);
     if (_currentLSB == 0.0f) {
-        _currentLSB = caluculate_currentLSB(maxCurA);
+        _currentLSB = calculate_currentLSB(maxCurA);
     }
 }
 
@@ -329,7 +329,7 @@ bool UnitINA226::begin()
     }
 
     // Set calibration
-    uint16_t cal = caluculate_calibration(_shuntRes, _maxCurrentA, _currentLSB);
+    uint16_t cal = calculate_calibration(_shuntRes, _maxCurrentA, _currentLSB);
     if (!writeCalibration(cal)) {
         M5_LIB_LOGE("Failed to writeCalibration %u", cal);
         return false;
@@ -593,13 +593,13 @@ bool UnitINA226::powerDown()
 bool UnitINA226::softReset(const bool all)
 {
     ModeCfg mc{};
-    uint16_t cal{};
     _periodic = false;
 
     if (read_configuration(mc.v)) {
         mc.reset(true);
         if (write_configuration(mc.v)) {
             m5::utility::delay(2);
+            uint16_t cal{};
             if (read_configuration(mc.v) && mc.v == DEFAULT_CONFIG_VALUE && readCalibration(cal) && cal == 0) {
                 // Default config 0x4127 is ShuntAndBus continuous mode,
                 // but leave _periodic false; caller manages it via powerDown/startPeriodicMeasurement
@@ -723,7 +723,7 @@ bool UnitINA226::read_measurement(ina226::Data& d)
     uint8_t reg{SHUNT_VOLTAGE_REG};  // 0x01
     for (uint_fast8_t i = 0; i < 4; ++i) {
         if (_measureBits & (1U << i)) {
-            ret &= readRegister16BE((uint8_t)(reg + i), d.raw[i], 0);  // reg 0x01 - 0x04
+            ret &= readRegister16BE(static_cast<uint8_t>(reg + i), d.raw[i], 0);  // reg 0x01 - 0x04
         }
     }
     d.currentLSB  = _currentLSB;
diff --git a/src/unit/unit_INA226.hpp b/src/unit/unit_INA226.hpp
index af72f7e..8c777a5 100644
--- a/src/unit/unit_INA226.hpp
+++ b/src/unit/unit_INA226.hpp
@@ -143,7 +143,7 @@ public:
 protected:
     /*!
       @brief Constructor
-      @param shuntRes Shunt resistor (O)
+      @param shuntRes Shunt resistor (Ohm)
       @param maxCurA Maximum measure current (A)
       @param curLSB currentLSB
      */
@@ -173,7 +173,7 @@ public:
 
     ///@name Properties
     ///@{
-    //! @brief Gets the shunt Resistor (O)
+    //! @brief Gets the shunt Resistor (Ohm)
     inline float shuntResistor() const
     {
         return _shuntRes;
@@ -229,7 +229,7 @@ public:
     }
     /*!
       @brief Start periodic measurement
-      @param rate Sampling Sampling rate
+      @param rate Sampling rate
       @param sct Shunt conversion time
       @param bct Bus conversion time
       @param current Measure current if true
@@ -273,7 +273,7 @@ public:
       @brief Measurement single shot
       @details Measuring in the current settings
       @param[out] data Measured data
-      @param rate Sampling Sampling rate
+      @param rate Sampling rate
       @param sct Shunt conversion time
       @param bct Bus conversion time
       @param current Measure current if true
@@ -299,13 +299,13 @@ public:
     bool readMode(ina226::Mode& mode);
     /*!
       @brief Read the sampling rate
-      @param[out] rate Samling rate
+      @param[out] rate Sampling rate
       @return True if successful
      */
     bool readSamplingRate(ina226::Sampling& rate);
     /*!
       @brief Write the sampling rate
-      @param rate Samling rate
+      @param rate Sampling rate
       @return True if successful
       @warning During periodic detection runs, an error is returned
      */
diff --git a/src/unit/unit_KmeterISO.hpp b/src/unit/unit_KmeterISO.hpp
index 4063925..b14d4c5 100644
--- a/src/unit/unit_KmeterISO.hpp
+++ b/src/unit/unit_KmeterISO.hpp
@@ -36,11 +36,11 @@ enum class MeasurementUnit : uint8_t {
 struct Data {
     std::array<uint8_t, 4> raw{};  //!< Raw data
 
-    //@note Unit depends on setting
+    //! @note Unit depends on setting
     inline float temperature() const
     {
-        return static_cast<int32_t>(((uint32_t)raw[3] << 24) | ((uint32_t)raw[2] << 16) | ((uint32_t)raw[1] << 8) |
-                                    ((uint32_t)raw[0] << 0)) *
+        return static_cast<int32_t>((static_cast<uint32_t>(raw[3]) << 24) | (static_cast<uint32_t>(raw[2]) << 16) |
+                                    (static_cast<uint32_t>(raw[1]) << 8) | static_cast<uint32_t>(raw[0])) *
                0.01f;
     }
 };
@@ -63,7 +63,7 @@ public:
         bool start_periodic{true};
         //! periodic interval(ms) if start on begin
         uint32_t interval{100};
-        //! //!< measurement unit if start on begin
+        //!< measurement unit if start on begin
         kmeter_iso::MeasurementUnit measurement_unit{kmeter_iso::MeasurementUnit::Celsius};
     };
 
@@ -97,12 +97,14 @@ public:
 
     ///@name Properties
     ///@{
-    /*! Gets the measurement unit on periodic measurement */
+    //! @brief Gets the measurement unit on periodic measurement
+    //! @return Current measurement unit
     kmeter_iso::MeasurementUnit measurementUnit() const
     {
         return _munit;
     }
-    /*! Set the measurement unit on periodic measurement */
+    //! @brief Set the measurement unit on periodic measurement
+    //! @param munit Measurement unit to set
     void setMeasurementUnit(const kmeter_iso::MeasurementUnit munit)
     {
         _munit = munit;
@@ -173,7 +175,7 @@ public:
       @return True if successful
       @warning During periodic detection runs, an error is returned
      */
-    bool measureSingleshot(kmeter_iso::Data& d,
+    bool measureSingleshot(kmeter_iso::Data& data,
                            const kmeter_iso::MeasurementUnit munit = kmeter_iso::MeasurementUnit::Celsius,
                            const uint32_t timeoutMs                = 100);
     /*!
@@ -184,7 +186,7 @@ public:
       @return True if successful
       @warning During periodic detection runs, an error is returned
      */
-    bool measureInternalSingleshot(kmeter_iso::Data& d,
+    bool measureInternalSingleshot(kmeter_iso::Data& data,
                                    const kmeter_iso::MeasurementUnit munit = kmeter_iso::MeasurementUnit::Celsius,
                                    const uint32_t timeoutMs                = 100);
     ///@}
diff --git a/src/unit/unit_av_base.hpp b/src/unit/unit_av_base.hpp
index 8c40049..7cf4c15 100644
--- a/src/unit/unit_av_base.hpp
+++ b/src/unit/unit_av_base.hpp
@@ -24,6 +24,9 @@ class UnitAVmeterBase : public UnitADS1115 {
     M5_UNIT_COMPONENT_HPP_BUILDER(UnitAVmeterBase, 0x00);
 
 public:
+    //! @brief Constructor
+    //! @param addr I2C address of the ADC
+    //! @param eepromAddr I2C address of the calibration EEPROM
     explicit UnitAVmeterBase(const uint8_t addr = DEFAULT_ADDRESS, const uint8_t eepromAddr = 0x00);
     virtual ~UnitAVmeterBase()
     {
@@ -31,11 +34,16 @@ public:
 
     virtual bool begin() override;
 
+    //! @brief Gets the calibration factor for the current gain setting
+    //! @return Calibration factor
     inline float calibrationFactor() const
     {
         return _calibrationFactor;
     }
 
+    //! @brief Write the gain and update calibration factor
+    //! @param gain Gain setting
+    //! @return True if successful
     virtual bool writeGain(const ads111x::Gain gain) override;
 
 protected: